An image forming apparatus, such as a printer or a multi-function peripheral (MFP), or the like is typically provided with an application environment of a web browser. A user generates a graphical user interface (GUI) on an application screen via hypertext markup language (HTML), and displays and operates the application screen using a web browser. To determine if the generated application screen operates normally, the user performs a test. For this test, the user causes an operation panel of an image forming apparatus to display the application screen, and performs an operation to verify whether the application screen operates properly by operating all operation items. While the verification operation is performed on the application screen, the user occupies the image forming apparatus. Due to this inconvenience, a method is known to test the application screen without the need to use any hardware device. For example, a virtual unit is available. In the virtual unit, an application program runs without using the hardware unit to cause a user to visually recognize the operation of the application program.
In the known method, the virtual unit as a software component needs to be generated to cause the application program of the hardware unit to be operative without using the hardware unit.